The Effects Of AM Fungi On The Growth Of Cassava

Cassava (Manihot esculenta),one of three tuberous crops in the world, is one of the main raw materials in producing alcohol,the development of cassava industry is meaningfull to energy crisis remission and environmental protection.Cassava is a typical mycorrhizal crop. To investigate the possibility of using arbuscular mycorrhizal fungi on tuber crops culture, experiments were conducted with cassava’South China NO.205’as test crop to screen the advantageous fungi and to study the effects of AM fungi on the infection rate and the growth of cassava. The effects of AM fungi, including Glomus intraradices (Gi), G. manihotis (Gm) and Acaulospora tuberculata (At), on the growth of cassava by the pot culture method and the field trial with single inoculum treatments and mixed inocula treatments were studied. Results showed that all the tested AM fungus could form vesicular-arbuscular mycorrhizae(VAM,AM)after inoculation. Examinations were done in root samples of different treatments at different growth stages which indicated that there were large differences in colonization ability and growth of different inocula.Details as follows.(1) Single inoculum treatment:In the pot culture,there was higher infective frequency in Gm treatment, which was56.7%-73.3%,specially in the early to middle stages; the growth of plant and the absorption of phosphorus in stem were improved by inoculating Gm,and Gi, in which the average height of cassava were respectively122.7cm and117.1cm,superior to control check(CK). The dry weight of overground part and stem respectively increased1.9g and1.0g,meanwhile the content of phosphorus in leaf and stem were significant superior to CK. The effects on the growth of cassava by inoculating Gi and At were not obvious. In the field trial,the infective frequency were respectively80.0%-100.0%and70.0%-93.3%,and weight of fresh tuber respectively increased58.0%and91.7%by inoculating Gm and Gi,which were higer than control check. The experimental results revealed that incoculation with AM fungi made positive contributions to improve the quality of cassava.In harvest, content of total nitroge、total phosphorus and total potassium order in tuber were all Gi>Gm>CK,and content of starch order was Gm>Gi>CK. Incoculation with Gi and Gm could increase biomass accumulation.The average height were262.4cm and259.5cm by inoculating Gi and Gm,which were separately8.6cm and5.7cm higher than CK.(2) Mixed inoculua treatment:In the pot culture, the treatments of Gi and Gm (2G) or2G+At made higher and stable infectation,the infect frequency were62.2%-80.0%and63.3%-86.7%;the average heights of cassava were obviously higher than CK in the mid-to late stage(24-29weeks).The phosphorus content of leaf and stem were higher than CK,in which the phosphorus content of stem was obviously higher.The effects of mixed inoculum treatments of2G was better, especially in biomass accumulation.In general, the effects of mixed inoculum treatments of Gi and Gm (2G) or2G+At were better than single inoculum treatments, especially in biomass accumulation by inoculating2G and infection intensity by inoculating2G+At. In the field trial, Gm vaccination in early with a higher rate of infection, to improve the tuber starch content in plant height growth, stimulative cassava late effects. Mixed inoculation of2G treatment on cassava tuber, tuber weight in total nitrogen, total potassium content and starch content on the effect than the single strain Gm.(3) The effect of arbuscular mycorrhizal(AM) fungi on utilization of insoluble phosphate and the growth in cassava was studied by pot culture. The cassava was grown in the sand and AIPO4was supplied as a source of P, inoculated with Glomus manihotis. The results showed that cassava could utilize some amount of AIPO4but with Gm to help improve cassava utilization of sparingly soluble P ability; the inoculation of AM fungi mycorrhizae effect with100mg.kg-1phosphate levels of immunization effect is better than that of1000mg.kg-1phosphate fertilizer levelsTwo strains and two portfolio of hign effective AM fungi to cassava growth were screened from the3inocula in the pot culture and field trial.